Hydraulic power devices



Oct. 8, 1963 R. D. ACTON HYDRAULIC POWER DEVICES 2 Sheets-Sheet 1 Filed Feb. 19, 1958 wNN \NN MM INVENTOR.

Oct. 8, 1963 R. D. ACTON ,106,063

HYDRAULIC POWER DEVICES Filed Feb. 19, 1958 2 Sheets-Sh eet 2 JJK 1 AI .lA

"Z- WL 3,106,063 HYDRAULIC PGWER DEVICES Russel l). Acton, 1219 Robinson St., Danville, Ill.

Filed Feb. 19, 195s, Ser. No. 716,138

25 Claims. (CI. 60-52) This invention relates to a hydraulic power device for tractors. More specifically it relates to an indicating and stroke control system for hydraulic cylinders.

In the operation of farm equipment particularly with tractor drawn tools, hydraulic cylinders operated by a valve on the tractor have been widely used for many years for controlling operating depth and other functions of the working elements and tools. Several different means such as stop collars on the piston rods of the remote control cylinders have been employed to regulate the depth of the working tool or other functions such as the cutting height of a combine platform. Other means have also been used to set the stop on the remote cylinder by electrical means from the operators station. None of these devices have accomplished the very desirable feature of enabling the operator to observer the position of the stop while looking straight ahead in the direction of travel of the tractor. Neither have any of the prior devices been operable with a plain simple standard low cost cylinder single or double acting.

A principal object of the present invention is to provide a hydraulic system including a remote reversible hydraulic motor with a combined stop indicator independent of the motor for regulating the stroke of the motor and for indication of the motor position in its cycle of operation. A subsidiary object is the provision of such a stop indicator device as a unit usable with any existing hydraulic system. 7

Another principal object is to provide a tractor with a remote control cylinder on a drawn tool with a hydraulic system having a fluid metering depth indicating means on the tractor ahead of the operator and means readily available by the tractor operator for setting a stop control for the cylinder.

Another more specific object is to provide a combined stroke control and indexing unit for remotely located hydraulic cylinders with over-ride means following the stop. Another specific object is to provide a stop control unit having a plurality of stops at spaced intervals. Another specific object is to provide such a device with a stop effective when approached from either direction.

Another principal object is to provide a self contained stop indicator for hydraulic systems having a latchable valve with pressure releasable detent operable by pressure buildup in the system brought about by the stop indicator. Another object is to provide a self contained hydraulic stop indicator with rephasing means whereby remote cylinders may be connected to the indicator in out of phase relationship.

The above objects and others which will be apparent from the detailed description to follow are accomplished by structures such as shown in the drawings in which:

FIGURE 1 is a diagrammatic drawing of a portion of a tractor with a hydraulic system indicated which incorporates a stop indicator. \FIGURE 2 is a vertical side view partly broken away in section showing a stop indicator device. FIGURE 3 is a view of the upper portion of FIGURE 2 at right angles thereto and partly broken in section. FIGURE 2 also includes a diagrammatic view of the hydraulic circuit employed in FIGURE 1.

FIGURE 4 is an elevation partly in section showing a modification of the indicator and stop device and includes a diagram of the complete hydraulic system. FIGURE 5 is a section on the line '55 of FIGURE 4. FIGURE 6 is a section on the line 6 6 of FIGURE 4. FIGURE chassis.

7 is a section on the line 7-7 of FIGURE 6. FIGURE 8 is a section on the line '8$'of FIGURE 5. FIGURE 9 is a section on the line 99 of FIGURE 5.

FIGURE 10 is an elevation mostly in section showing diagrammatically, a simplied form of stop and indicator device.

In the drawings a conventional farm tractor is diagrammatically illustrated. The rear end of the chassis or body 10 is shown with one drive or traction wheel 1-1, the other rear wheel being removed to better show the arrangement of the hydraulic system. An operators seat 12 is shown as being carried by a battery housing 13 mounted on the frame or body 10 at the rear end thereof. A fuel tank 14 is shown positioned ahead of the operators station and a steering wheel 15 is located ahead of the operators seat.

A reservoir 16 is connected by a fluid conduit 17 with a pump 18 adapted to be driven inthe usual manner by the engine of the tractor. A fluid conduit 19 leads from the pump 18 to a conventional 4 way fiu-id flow control valve. A control handle 21 operatively associated with the valve '20 is positioned so that it is readily available to the operator. A conduit 22 connects the low pressure returnfrom the valve 20 with the reservoir. A conduit 23 connects the valve 20 with a junction block 24 through which by means of another conduit 25 fluid is carried to one half 26 of a break-a-way coupler. This type of coupler which is standard on almost all farm tractors operating trailing implements is constructed to seal the ends of the conduits or hoses with which it is connected when the coupler is broken so that there is no substantial escape of fluid even under high pressure.

The coupler halves can also be connected with the fluid. under working pressure without the escape of 'any substantial amount of fluid.

A second coupler half 27 is connected by a hose 2.8 with the piston rod end of aworking ram or cylinder 29, the piston rod 30 of which is pivotally connected to a bracket 31 mounted on a plow beam 32. Said beam is pivotally connected to a drawbar structure 33 carried by the tractor A moldboard plow 34 is shown carried by the beam 32.

The beam 32 also has a forwardly mounted bracket 35 which provides for pivotal mounting of a crank arm 36 which at its upper end is pivotally connected to the forward end of the cylinder-29. At its lower end the 1 crank arm 36 is secured to a rolling gauge wheel 37 which is positioned relative to the moldboard 34 so as to effectively gauge the working depth of the plow. It is to be understood that the showing of a tractor and implement is for the purpose of showing the operation of the hydraulic system which is especially designed for and has novel functional relationship with a tractor and implement combination as shown.

A conduit 38 connects the rear end of the working cylinder 29 with the coupler half 27. A conduit 39 connects the coupler half 26 with the junction block 24 and therethrough with a conduit 40. The conduit 40 connects with an indicator and stroke control device designated in its entirety by the reference character S, a conduit 41 connecting said device with the valve 20. It will be noted that the indicator device 6 is located ahead of the openators station so that an operator may readily observe it while looking for-ward in the direction of travel of the tractor. This arrangement is a significant part of applicants improvement in power lift systems for tractors.

As diagrammatically illustrated the indicator unit S includes :a barrel or body portion in the form of a cylinder 42, a base 43 secured by any means such as by welding as shown to the cylinder, and a head 44 secured to the upper end of the cylinder. A piston 45 is mounted for reciprocation in the cylinder 42 being maintained in leak J free relationship with a conventional O-ring 46. Said piston is provided with a large bore 47 opening to the bottom side of the piston for a ball 2-8 seated by a spring 49 held at its lower end by an annular groove t formed near the lower end of the bore 47, against a seat formed by a bore 51 leading from the upper end of the bore 47 to the upper face of the piston. A second check valve of the same construction but opening in the other direction is mounted in the piston. Another main bore 52, a secondary bore 53 and a ball 53 are shown in FIGURE 2.

An index means illustrated as an indicator or pistion rod 54 extends through a bore 55 formed in the head 44, leakage being prevented by an O-ring 56. The lower end of the rod 54 is secured to the piston 45 by a pin 57. At its upper end, the rod 54 has a shallow recess 58 in which a resilient rubber O-ring 59 is positioned with about half of the diameter of the ring projecting beyond the cylindrical surface of the rod.

The base 43 and the head 44 have respectively bores 59 and 60 which are on the axis of the cylinder 42.. The bore 59 joins a larger bore 61, the upper end of which terminates at the upper face of the head 43 to form a seat for a fluid supply control means in the form of a valve 62. The bore 60 joins of a larger concentric bore 63 which terminates at the lower face of the head 44; to form a seat for a fluid supply control means in the form of a valve 64. The valve structure is completed by a rod having an upper stem 65 closely fitting the bore 69 for reciprocation therethrough, an integral body portion 66 extending between the valves 64 and 6 2 and a lower stem 67 which slideably extends throught he bore 59. The body portion 66 is larger than the stems thereby providing shoulders against which the valves are tightly pressed. An O-ring 68 is mounted in a recess at the lower end of the stem 67 to provide a high pressure seal. An O-ring 69 is mounted in a recess where the stem 65 passes through the bore 69 to provide a seal at the upper end. A bore 79 formed in the head communicates with the bore 63 to form a fluid connection with the conduit 40. A similar bore 71 in the base communicates with the bore 61 to form a fluid connection with the conduit 42.

Two supporting and guard rods 72 and 73 are secured to the head 44 in transverse alignment with the indicator rod 54. The upper ends of the rods '72 and 73 are secured to a plate 74 which extends over the valve structure and is provided with a bore 75 through which the valve stem 55 extends. A preloaded spring 76 is secured by a screw 76a'to the plate 94, said spring abutting the upper surface of the plate above the bore 75 in position to be engaged by the stem 65 when it is moved upward- 1y. A similar preloaded spring 77 abutting the bottom surface of the base over the bore 5? is secured to the base by a screw 78.

An adjustable stop member 79 has a bore 80 which slideably fits the stem 65 which extends through it. The member 79 also is formed with a bore 81 having counter bores 82 at each side thereof. The bore 31 is slightly smaller than the outside diameter of the O-ring 59 when it is installed in the recess 58. The member 79 is guided in its sliding movement on the stem 65 by loose sliding contact with the rods 72 and 73. A locking member for the member 79 consists of a strip of spring material having a portion 83 extending above the member 79', a portion 84 extending below the member 79 and a joining portion 35. The portions 33 and 84 have respectively holes 83' and 84 through which the stem 65 loosely extends duit 23 or the conduit 42 is also provided with a conventional two-way acting preloaded spring device 86 effective to return the valve spool 87 from either of its fluid delivering positions to neutral centered position. A small cylinder 83 has a piston 89 which carries a small piston rod 95? extending through the closed lower end of the cylinder in position to engage either of two recesses 91 at an extended end of the valve spool 87 for latching the valve in either of its operative positions. A compression spring 92 urges the detent into latched engagement with the spool 37. A conduit 93 connects the conduit 19 with the cylinder 88 so that a pressure build up in the pressure side of hydraulic system will unlatch the valve spool 87 whereby it is returned to neutral position.

The operation of the system above described in detail is simple and efiective to give an operator control of the operating position of the remote working hydraulic motor or ram as such hydraulic cylinders are frequently designated. A tractor operator will normally hook up to an implement and connect the two halves 26 and 27 of the break-a-way coupler. It will be assumed that there is an out of phase relationship between the piston of the remote working clinder and the position of the piston 45 of the stop and indicator device. It should be mentioned that the displacement of the remote cylinder must be equal to or less than the displacement of the stop device. Assuming that the valve 26 is operated so fluid will flow to force a piston 30' downwardly, then the piston 45 will also move downwardly. If the phase relationship of the two pistons is such that piston 3% reaches the bottom of its cylinder first, then a dead stop is reached. If this occures then the operator reverses the fluid flow and forces the piston 39' upwardly, in both instances, the piston 45 which is in series with the piston 30' moves with the same displacement. As the piston 30' moves upwardly the piston 45 may reach the top of its stroke first depending on the original phase relationship. If this happens fluid bypasses the low pressure check valve 53 and the piston 3t) continues to move until it reaches the top end of its stroke. Phasing is then complete with both pistons at the top end of their respective strokes. If the cylinder 29 has a smaller displacement than the cylinder 42 the piston 45 may not reach the top end of its stroke and series movement of the pistons 45 and 345 will take place at an intermediate range of the cylinder 42.

There is another phasing possibility. If the piston 34? is initially forced down for phasing and the piston 45 reaches the bottom end of its stroke first, then fluid bypasses the low pressure check valve 51 until the piston 36' reaches the lower limit of its stroke. Phasing is then complete. The piston 45 then becomes a fluid metering means of liquid flowing to the remote cylinder. In any event, to phase the device when a different remote cylinder is added, it is only necessary to run the remote cylinder as far as it will go or to the end. of its stroke in both directions. After phasing has been accomplished it is not necessary to rephase except which another cylinder is connected.

To set the stroke of the remote cylinder, which in the tractor and plow combination illustrated would amount to setting the working depth of the plow, the operator first adjusts the position of the piston in the remote cylinder until the desired working depth is selected. The indicating cylinder with its piston acts as a metering means to measure the liquid being delivered to the remote cylinder. The lower stop 79 is then moved manually until the restricted bore 81 is against the stop actuating ring 59 on the indicator rod 54. Thereafter when the implement is lifted as for turning at the end of the field and lowered, the stop member is engaged :by the 0-ring' on the indicator rod 55. As previously pointed out the internal valve assembly is hydraulically balanced and is further held in a neutral centered position by the preloaded springs and 77. These springs have a suflicient preload to overcome the friction of the O-rings 68 and 69. The friction due to compression of the O-ring 59 in engagement with the restricted bore 81 is sufficient to overcome the compres sion of the spring '7 7 and to move the valve 62 towards its seat. After a certain movement a pressure diflerenti al builds up back of the valve 62, which closes it, blocking fluid flow and building up relief valve pressure in the pump side of the system. The action releases the detent on the valve spool 87 and the valve is returned to neutral position. Although such a stop arrangement has a special utility when used in combination with a pressure releasable detent type of control valve, the same stop function is obtainable with any manually operated valve, the operator merely releasing the valve when the blocker valve operates.

It is obvious from the construction that the action is the same in the reverse direction as the O-ring 59 engages the restricted bore 81 from the bottom side. This lifts the valve structure against the spring 76 with the valve 64 closing to block the flow of fluid. In either direction of operation, to over-ride the stop, a restricted orifice 94 is provided between the bore '71 and the lower end of the cylinder and 'a bore 95 is provided in the head 44 between the bore 7% and the interior of the cylinder. The bores are of such size that they will not bypass sufiicient fluid to reduce the pressure materially when the pump is operating and when the valve spool is in position to deliver fluid to the working cylinder. In either direction of operation, as soon as the O-ring 59 has passed through the restricted bore 81, the springs 76 and '77 act to bring the blocker valve assembly back to neutral position. The operator may then over-ride a selected amount or latch the valve and complete the entire stroke of the cylinder by again latching the valve. It will be understood that there is a wide combination of possibilities since a plurality of stops may be used and since the mechanism is such that the stopping action is symmetrical when the stops are approached from either direction.

The bypass bleeds 94 and 95 may be calibrated as desired, may be made adjustable by the use of small conventional needle valves or maybe eliminated if over-ride is not desired.

FIGURES 4 to 8 show a modification which while operating with substantially diiferent mechanisms functions very much the same as the structure of FIGURES l to 3. The hydraulic system in this modification bears some of the same reference characters as in the previously described form. The indexing and stop device will be separately described.

A cylinder 96 is \closed at its upper end by a head 97 and at its lower end by a base 98. The base has an opening for connecting the conduit 42. The head is formed with a transverse bore 99 lying to one side of the center and a smaller bore 100 forming a T with the bore 99. An annular recess 1191 formed internally of the bore 99 intermediate its ends communicates with a passage 102 ,as shown in FIGURE 8 forming a communication between the recess 101 and the upper end of the cylinder 96. The outer end of the bore 9? is threaded to receive the c nduit 40.

Axially of the cylinder 96, the head 97 is provided with a bore 103 through which an indicator rod 1414 slideably extends, being sealed by an O-Illlg 195. A larger bore 106 concentric with the bore 103 receives the lower end of a tube 107 Within which the rod 104 is adapted to reciprocate. A set screw 108 holds the tube 107 against movement rigid with respect to the head 97. A vertical slot 109 is formed lengthwise in the tube 197 to provide a track for the reciprocation of a transverse pin 110 fitted in the top of the rod 164. A member 111 is secured to the top of the tube 107. The rod 104 is secured to the piston 45 in the same manner as in the previously described form, all piston parts having the same reference characters.

A bore 112 extends vertically into the head 97 from the upper face through the dead end of the bore and a substantial distance below. A balance bleed 113 connects the bottom of the bore 112 with the outside atmosphere. An oscillating valve actuating rod 114 slideably extends through the bore 112 to the lower end thereof being sealed by an upper O-ring 115 and a lower O-ring 116. The upper end of the rod 114 is received in a bore 117 rformed in the member 111. The rod 114 is hydraulically balanced and held against endwise movement.

A cylindrical valve member 118 is fitted for reciprocation in the bore 99 normally when in neutral position extending partially into the recess 101 thereby permitting free fluid flow through the conduit 4-0. Through the bore 100, a valve actuating pin 119 is insertable for being pressed or otherwise fitted in a transverse bore formed at the portion of the rod 114 which passes through the bore 1%. Said pin has a head portion which abuts the wall of the bore 169, being normally held thereagainst by a spring 12h which abuts the valve member 118. Said valve memher is formed with a bore 121 to provide for balancing the hydraulic pressure at each end of the member.

Two identical stop members 122 are shown slideably secured to the valve actuating rod 114. Each has a bore through which the rod extends and is provided with a set screw 123 to secure the member to the rod against reciprooation and rotation. Each member 122 has a projecting cam 124 positioned and shaped to engage the pin 11% when it is approaching from either direction and to oscillate the valve actuating rod 114-. Such oscillation is V in the angular direction such as to move the pin 119 against the valve member 113 and to move said member past the recess 1411 thereby blocking the flow of fluid.

At the outer end of the bore 100, a combined closure and valve member 125 is rotatably mounted, a screw driver slot being provided in the head for rotating the member. An O-ring 126 seals the member 125 and a snap ring 127 holds it in position. From the inner end, a bore 128 is [formed in the member 125 and a plurality of radial bores 129 communicate with the bore 128. Said bores provide an adjustable means for varying the rate of bypass when the blocker valve is in flow blocking position. As shown in FIGURE 9, a small port 130 is formed in thehead $7 between the bore 100 and the lower face of the head. The bores 129 can be moved with respect to this port iior flow rate adjustment.

Phasing is accomplished in the same manner with this form of the device as with the form shown in FIGURES 1 to 3 and installation in a tractor power lift system would be the same. The valve member 118 being hydraulically balanced is equally effective to block fluid flow when actuated by movement of the cam pin 110 in either direction. The rate of bypass for over-ride may be adjusted so that sufficient resistance to flow is brought about to actuate a detent when a pressure unlatchable detent is used. If a plain manually operated control valve is used the bypass valve member will be set quite tight so as to provide a time element to compensate for the reaction time of the operator necessary to bring the valve back to neutral pos tion. Multiple stops may be used with this device to limit up and down travel of the remote hydraulic ram or motor. Stepped stops may also be employed in the same direction of movement. meet different operating conditions, moreover, the operator observes at all time the distance be is altering, overriding or moving away from any stop location.

I In FIGURE 10 a modification is shown which eliminates several parts and functions of the more versatile from already described. A cylinder 130 is closed by a head 131 and a base 132. The base has a threaded opening for connecting the conduit 42 of FIGURE 1.

an indicator rod 134 slideably extends, leakage being prevented by an O-ring seal 135. The rod 134 is connected to a piston 45 being identical with the piston shown in FIGURE 3 and having the same valves 51 and 53'. This This system is very versatile to The head 131 has an axial opening or bore 133 through which 7 piston is also sealed in the same manner as the piston of FIGURE 2, the seal not being shown because of the small scale.

The head 131 is also provided with a transverse chamber 136 terminating in a threaded bore for the connection of the conduit 49 of FIGURE 1. A vertical bore 137 joins the chamber 136 with the upper face of the head 131. A valve stem 138 extends through said bore and carries a valve 139 within said chamber. A second vertical bore 140 in axial alignment with the bore 1.37 connects the chamber 136 with the lower face of the head 131 and with the interior of the cylinder 13%. The junction of the bore 148 with the chamber forms a valve seat against which the valve 139 may be seated to block flow of fluid from the cylinder out through the chamber. The rod 134 receives an adjustable stop member Mil which has a vertical bore through which the rod slideably extends. A screw 142 threaded in the member 141 provides means for securing the stop member at any location along the rod 134 in positions to engage the upper end of the valve stem 138.

in the construction of FIGURE 10 the initial phasing is the same as in the form already described. With the stop member in a setting as shown and with fluid flowing in through the chamber 136 and into the cylinder through the bore 146, the piston 45 moves downwardly with fluid flowing out through the base 132. When the stop member reaches the valve stem 13%;, the valve will be moved downwardly until it seats at the upper end of the bore 140 and blocks the flow of fluid. It will be evident that with this simple form of the device no over-ride can be readily provided as continued movement of the piston 45 would move the frictionally held step member 141 which would disturb the setting for a subsequent operation. Such an accidental over-riding would not however result in any harm to the device and would merely require the operator make a new setting.

It will be noted that no return spring is employed on the valve 139 as the valve structure including the stem is hydraulically unbalanced by the area of the stern 138. The valve will therefore always move to open position when not held shut by some other force such as pressure on the stem 13%. There is another action on the valve 139. As it is moved to closed position by the stop member 141, the opening for fluid flow becomes so restricted that pressure builds up on the back side of the valve. When this pressure becomes greater than the pressure in the other direction on the stem 13?, the valve 139 jumps shut and stays shut as long as pressure on the inlet side is correspondingly great. When lifting takes place and the pressure is reversed the valve immediately opens the amount it had moved away from the stop member 14-1 providing for fluid flow of such volume that a pressure unlatched detent valve as previously described would not be operated before sufficient movement had taken place to move the stop member away from the valve stem 133. It is to be understood that in this form of the device multiple stops are not possible and a stop is provided in the down direction only. There are some uses where a simple inexpensive device of this kind meets the requirements.

To show the scope or" applicants invention three different forms have been shown and described. There are many ramifications utilizing the principles disclosed dif fering in means employed and in the number of the features used. It is to be understood that all structure falling within the scope of the following claims are included as parts of applicants invention or discovery.

1 claim:

1. For a hydraulic power lift system utilizing a remote working cylinder and piston device and having a pump, a reservoir and a control valve, a stop indicator device including a cylinder, a piston therein, closures at the ends of the cylinder, indicating means secured to the piston and extending through one of the closures, fluid conducting means extending through each closure from the outside to the inside of said cylinder, a blocker valve positioned and operable to close one of said conducting means, valve operating means connected to said valve and having a portion extending along the path of movement of said indicating means, a stop member adjustably secured to said portion, cam means carried by the indicating means and engageable with said stop member to operate the blocker valve at the location determined by the stop member setting, coupling means for connection with the remote working cylinder and piston device and conduits for connecting the stop indicator device to the control valve and the coupling means.

2. A device as set forth in claim 1 in which oppositely opening check valves are mounted in the piston for phasing the stop indicator piston with respect to the piston of the remote working cylinder.

3. A device as set forth in claim 1 in which the cam means is provided with portions constructed to engage the stop member when approaching it from either direction whereby the valve operating means is operable by movement of said cam means past said stop member in either direction.

4. A device as set forth in claim 1 in which the control valve is provided with a latch to hold it in fluid delivering position and with means to return it to neutral position and in which a pressure operable means is provided and actuated by functioning of the blocker valve to unlatch the control valve whereby it is returned to neutral position.

5; A device as set forth in claim 1 in which the blocker valve has a portion of its operating means extending through each closure to the atmosphere whereby the valve is hydraulically balanced.

6. A stop indicator device for hydraulic systems used with a reciprocating hydraulic motor, said step indicator comprising a cylinder, a piston mounted for reciprocation in the cylinder, closures at each end of the cylinder, indicating means secured to the piston and extending through one of the closures, fluid conducting means extending through each closure from the outside to the inside of said cylinder, a blocker valve positioned and operable to close one of said fluid conducting means, actuating means connected to said valve and extending along the path of movement of the indicating means and a stop member adjustably secured to the actuating means in a location to be engaged by the indicating means to operate the blocker valve.

7. A device as set forth in claim 6 in which oppositely opening check valves are located in the piston to provide for fluid flow therethrough in either direction.

8. A device as set forth in claim 6 in which the stop member and the indicating means are provided with cooperating means engageable with the indicating means moving in either direction whereby the valve actuating means is operable by movement of the indicating means in either direction.

9. A device as set forth in claim 6 in which a control valve is included for supplying fluid under pressure to the device, said valve being provided with a latch for holding it in fluid delivering position and with a pressure operated latch release for withdnawing said latch upon operation of he blocker valve.

10. A device as set forth in claim 6 in which the blocker Valve has a portion of its operating means extending through each closure to the atmosphere to provide a hy draulically balanced valve.

11. A device as set forth in claim 6 in which a plu rality of stop members are provided to determine a plurality of spaced positions of the indicator piston.

12. A device as set forth in claim 6 in which a by-pass fluid bleed is provided around the blocker valve and in which the stop member is over-ridable whereby movement of the piston may be continued after actuation of the blocker valve.

13. A stop indicator device for hydraulic systems used with a reciprocating hydraulic motor, said stop indicator comprising a cylinder, a piston mounted for reciprocation in said cylinder, closures at each end of the cylinder, indicating means secured to the piston and extending through one of the closures, fluid conducting means extending through each closure from the outside to the inside of the cylinder and terminating in an inwardly opening bore, a valve operating stem extending through each closure and connected to the piston, said stem extending through said bores on the axis thereof, a blocker valve secured to the stem at each end thereof adjacent the respective bore and adapted to selectively close said bores by reciprocation of said stem, said stem having an extension positioned along the path of movement of the indicating means, a stop member adjustably secured to said extenion, and means carried by the indicating means engageable with said stop member for actuating said blocker valves.

14. A device as set forth in claim 13 in which oppo sitely opening check valves are located in the piston to provide for flow of fluid in either direction therethrough.

15. A device as set forth in claim 13 in which a bypass fluid flow bleed is provided around one of the blocker valves.

16. A device as set forth in claim 13 in which a spring means is provided for holding the valve stem resiliently in a neutral position with both valves open.

17. A stop indicator device for hydraulic systems used with hydraulic reciprocating motors, said stop indicator comprising a cylinder, closures at each end thereof, reciprocating indicating means extending through the upper closure, a piston mounted for reciprocation in the cylinder, said indicating means being connected to said piston, fluid conducting means for the lower closure, a transverse bore formed in the upper closure, said bore extending the lower face of the closure to communicate with the interior of the cylinder and also provided with an outside connection for the supply and discharge of fluid, a hydraulically balanced reciprocating valve mounted in said bore and openable to block the flow of fluid therethrough, spring means for biasing said valve into an open position, a vertical valve actuating member mounted above the upper closure parallel to and spaced from the path of travel of the indicating means, said member extending into the closure and carrying an actuating pin therein positioned in engagement with the valve, cam means secured to the valve actuating member and manually adjustable along said member, and cam means carried by the indicating means arranged to operatively engage and oscillate the cam means on the valve actuating member and to thereby operate the blocker valve at a selected point in the stroke of the piston.

18. A device as set forth in claim 17 in which an adjustable bleed is provided around the blocker valve to provide for restricted fluid flow after closure of said valve.

19. A stop and indexing device for hydraulic systems comprising a closed fluid chamber, fluid metering means therein, means to supply fluid through said chamber, exteriorly visible index means structurally associated with said metering means and operable by said metering means in proportion to the flow therethrough, fluid supply control means structurally associated with the supply means, actuating means operatively and structurally associated with the fluid supply control means and the index means for restricting flow of fluid at a predetermined position of the index means and manually operably selecting means for setting said predetermined position.

20. A device as set forth in claim 19 in which a fluid :bypass is provided around the metering means and in which oppositely opening check valves are provided in said bypass.

21. A device as set forth in claim 19 in which a re stricted fluid flow bypass is provided around the actuating means for restricting flow of fluid whereby restricted flow can take place after closure of said valve.

22. A device as set forth in claim 19 in which the fluid metering means is operable with fluid flow in either direction and in which the stop means is constructed and arranged to be operable with fluid flow in either direction to operate the actuating means for restricting flow of fluid.

23. A device as set forth in claim 19 in which a control valve is included for supplying fluid under pres-sure to the device, said valve being provided with a latch for holding it in fluid delivering position and with a pressure operated latch release for withdrawing said latch upon operation of the actuating means for restricting flow of fluid.

24. A device as set forth in claim 19 in which a cylinder and piston device is connected to said chamber and in which the metering means has sufficient capacity of flow to operate said device a full stroke.

25. A hydraulic system for farm tractors having an operators station at the rear thereof and having a working tool connected thereto requiring adjustment comprising a reservoir, a pump, a control valve having a latch for holding the valve in fluid delivering position and fluid pressure operated means for releasing said latch, a cylinder and piston device, conduit means connecting all of said elements, said cylinder and piston device being adapted to be connected to the Working tool for regulating the operating position thereof, a stop mechanism operatively associated with said device, means operable from the operators station for adjusting the stroke setting of said stop mechanism, a blocker valve interposed in zone of said conduit means for controlling the fluid flow therethrough, said stop mechanism being operatively associated with said blocker valve, and indicator means mounted on the tractor ahead of the operator and operatively connected to move with the piston in the said device to show the position thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,261,444 Neubert Nov. 4, 1941 2,361,326 Silver Oct. 24, 1944 2,533,640 Ulrich Dec. 12, 1950 2,606,532 Ziskal Aug. 12, 1952 2,614,866 Ulrich Oct. 21, 1952 2,615,430 Fletcher Oct. 28, 1952 2,670,713 Jirsa Mar. 2, 1954 2,715,389 Johnson Aug. 16, 1955 

1. FOR USE HYDRAULIC POWER LIFT SYSTEM UTILIZING A REMOTE WORKING CYLINDER AND PISTON DEVICE AND HAVING A PUMP, A RESERVIOR AND A CONTROL VALVE, A STOP INDICATOR DEVICE INCLUDING A CYLINDER, A PISTON THEREIN, CLOSURES AT THE ENDS OF THE CYLINDER, INDICATING MEANS SECURED TO THE PISTON AND EXTENDING THROUGH ONE OF THE CLOSURES, FLUID CONDUCTING MEANS EXTENDING THROUGH EACH CLOSURE FROM THE OUTSIDE OF THE INSIDE OF SAID CYLINDER, A BLOCK VALVE POSITIONED AND OPERABLE TO CLOSE ONE OF SAID CONDUCTING MEANS, A VALVE OPERATING MEANS CONNECTED TO SAID VALVE AND HAVING A PORTION EXTENDING ALONG THE PATH OF MOVEMENT OF SAID INDICATING MEANS, A STOP MEMBER ADJUSTABLY SECURED TO SAID PORTION, CAM MEANS CARRIED BY THE INDICATING MEANS AND ENGAGEABLE WITH SAID STOP MEMBER TO OPERATE THE BLOCKER VALVE AT THE LOCATION DETERMINED BY THE STOP MEMBER SETTING, COUPLING MEANS FOR CONNECTION WITH THE REMOTE WORKING CYLINDER AND PISTON DEVICE AND CONDUITS 